Clean the text inside indexed tags

While testing the D7 port, I noticed that (for example) comment titles (in h2 tags) were getting their enclosing <a href=... indexed. Since various tags we index can be nested, probably the easiest thing to do is reuse our clenaup function on each value like this:

@@ -304,7 +303,7 @@ function apachesolr_add_tags_to_document(&$document, $text) {
       if (!isset($document->{$tags_to_index[$tag]})){
         $document->{$tags_to_index[$tag]} = '';
       }
-      $document->{$tags_to_index[$tag]} .= ' '. $matches[2][$key];
+      $document->{$tags_to_index[$tag]} .= ' '. apachesolr_clean_text($matches[2][$key]);
     }
   }
 }

this change is already being incorporated into the D7 version.